Spring got off to cold start in SLO County. Here’s when temperatures will warm up
A long spell of overcast days and low daytime temperatures has resulted in an unusually cold spring in parts of San Luis Obispo County.
A persistent marine layer, paired with a lack of strong winds, caused the chilly conditions occurring across most of the county, according to weather experts.
“This has been one of the gloomiest Aprils,” said John Lindsey, a retired PG&E marine meteorologist.
Exactly how cold has spring been so far in 2025? And when will temperatures finally warm up?
Here’s what to know about springtime weather conditions in SLO County:
San Luis Obispo area sees a cool start to spring
Temperatures in March and April were colder than usual in San Luis Obispo, although the area experienced a couple short periods of warm weather, according to Rose Schoenfeld, a National Weather Service meteorologist.
On average, high temperatures in March were about two degrees below normal in SLO, she said.
April also remained cool with high temperatures hovering 3.3 degrees below normal on average in the San Luis Obispo area, she said.
With the exception of a “mini-heat wave” in March and a week of warm weather in April, temperatures consistently stayed below normal for this time of year, she said.
What caused below-normal temperatures in SLO?
A more frequent and unusual marine layer led to cooler daytime temperatures in April, according to Lindsey.
A relentless marine layer often blocked the sun in San Luis Obispo and other coastal regions of SLO County, Lindsey said, keeping temperatures lower than usual during the day.
“We have May gray, June gloom, no sky July, Fogust, right?” he said, listing nicknames for the gloomy weather experienced by parts of SLO County during the spring and summer. “(There’s) really no word for April, because usually in April we have a lot of wind and clear skies.”
Northwestern breezes are typical throughout the spring in SLO County, but stretches of strong winds have failed to materialize so far in 2025, Lindsey explained.
“We just haven’t had the winds,” Lindsey said. “Usually, if the winds are strong enough, they’ll mix out that temperature inversion layer, and we’ll have sunny skies.”
Even when wind gusts have appeared, they’ve tended to remain under 25 mph, he said, resulting in a stubborn marine layer filled with pockets of fog and mist.
Paso Robles weather ‘close to normal’ this season
Spring got off to a chilly start in Paso Robles, but the North County city has since had fairly typical weather conditions for this time of year, weather experts said.
The Paso Robles area experienced a slightly colder March than usual, with high temperatures about 2.6 degrees below average on the whole, according to Schoenfeld.
April was very “close to normal” in Paso Robles, she said, with high temperatures in April just one-tenth of a degree colder than usual.
“However, periods of warmer and periods of cooler were pretty common,” Schoenfeld said, with lots of swings in temperatures and very few days of actually normal weather.
Lindsey said Paso Robles was undergoing an ordinary spring so far because of its location.
Due to Paso Robles’ distance from the ocean, he said, the city was able to avoid the fog and low clouds developing along the coastline that caused lower temperatures elsewhere.
When will temperatures warm up in SLO County?
San Luis Obispo will continue to see “May gray” conditions over the next few days, according to the National Weather Service’s latest seven-day forecast.
Patchy fog is expected to appear in the mornings and evenings, the weather agency said.
“On the coastline, it’s going to be gloom and doom,” Lindsey said. “(This) weekend, we should see another episode of increasing northwesterly winds and primarily clear skies.”
Temperatures will start to tick up Thursday when the high temperature is forecast to be 75 degrees in San Luis Obispo, the weather service said.
Friday and Saturday will be even hotter with highs of 83.
Sunday will be partly sunny with a high around 75, the weather service said.
In Paso Robles, the weather will be mostly clear with temperatures in the mid-70s, the National Weather Service said.
Temperatures are expected to rise Thursday when the high temperature is near 85, the weather agency said.
Friday and Saturday will be sunny with highs around 90 and 91 degrees, respectively.
Sunday will be mostly sunny with a high of 82.
What’s the long-term forecast for SLO County?
Temperatures will likely be colder than usual for most of May in San Luis Obispo County, according to the Climate Prediction Center’s two-week temperature outlook.
There is a 33% to 40% chance that temperatures will lean below average for the next eight to 14 days, the long-term forecast said.
The forecast is valid through May 18.
